Separable electrical connector with reduced risk of flashover

ABSTRACT

A separable loadbreak connector system includes mating electrical connectors. At least one of the electrical connectors includes an electrically-resistive housing having a generally conically-shaped interior bore. A semiconductive insert is disposed within a portion of the interior bore and presents an inner radial surface that defines a generally conically-shaped recess. An elongated probe assembly is disposed within the housing and includes a probe and a sheath of insulative material disposed over at least a portion of a length of the probe. A portion of the sheath extends in a radially outward direction from a base of the probe. An electrically-resistive insulative layer extends from the conically-shaped interior bore, along at least a portion of the inner radial surface of the semiconductive insert. The insulative layer extends radially inwardly in overlapping engagement with a portion of the sheath.

RELATED APPLICATIONS

This application is a divisional application of commonly-owned U.S.patent application Ser. No. 12/274,726, filed Nov. 20, 2008, entitled“Separable Electrical Connector with Reduced Risk of Flashover,” whichis a divisional application of U.S. patent application Ser. No.11/688,648, filed Mar. 20, 2007, now U.S. Pat. No. 7,572,133 entitled“Separable Loadbreak Connector System,” which is a continuation-in-partapplication of U.S. patent application Ser. No. 11/273,192, filed Nov.14, 2005, now U.S. Pat. No. 7,488,916 entitled “Vacuum SwitchgearAssembly, System and Method.” The complete disclosure of each of theforegoing related and priority applications is hereby fully incorporatedherein by reference.

BACKGROUND

This invention relates generally to bus systems and cable connectors forelectric power systems, and more particularly to separable insulatedloadbreak connector systems for use with modular bus systems.

Electrical power is typically transmitted from substations throughcables which interconnect other cables and electrical apparatus in apower distribution network. The cables are typically terminated onbushings that may pass through walls of metal encased equipment such ascapacitors, transformers or switchgear.

Separable loadbreak connectors allow connection or disconnection of thecables to the electrical apparatus for service, repair, or expansion ofan electrical distribution system. Such connectors typically include acontact tube surrounded by elastomeric insulation and a semiconductiveground shield. Insulated connector probe sleeves are cylindrical with avery small bonding area at the bottom portion of the interface cylinder.A contact piston is located in the contact tube, and a female contacthaving contact fingers is coupled to the piston. An arc interrupter, gastrap and arc-shield are also mounted to the contact tube. The femalecontact fingers are matably engaged with an energized male contact of amating bushing, typically an elbow connector, to connect or disconnectthe power cables from the apparatus. The piston is movable within thecontact tube to hasten the closure of the male and female contacts andthus extinguish any arc created as they are engaged.

The connectors are coupled to various sized and shaped pieces of buswork to complete the interconnection. Typically the bus work comprisesbus bars sized at the site of assembly to account for variousconfigurations of cable risers that carry cables to the electricalswitchgear. Such variety of component pieces makes repair or replacementof the components laborious in that each piece is generally custom madeand assembled. Insulation is provided between the bus bars and theactive switching elements to prevent electrical arcing. There are threecommon types of insulation typically used in conventional switchgear:oil, sulfur hexafluoride (SF₆) gas, and air. Each type of insulationinsulates each part of the switchgear from the other parts of theswitchgear (bus bar and active switching elements), and from the outersurfaces of the container of the switchgear. However, SF₆ gas isdifficult to contain, air requirements excessive spacing betweenenergized parts to be an effective insulator, and oil is also difficultto contain and is a fire hazard.

To increase a flashover distance between energized portions and groundedportions of the connector some known connectors are insulated usinglayers of insulative material covering a length of the energized portionand/or a semi-conductive portion. For example, an insulative layer maybe disposed within the recess of the connector along an inner surface. Aprobe assembly may be contained within the connector and aligned downthe axis of the recess. An insulative sheath covers a portion of theexterior of the probe. The insulative sheath surrounding the probe andthe insulative layer covering the inner surface of the housing areformed separately and insulative layer is expected to bond securely toinsulative sheath at an abutting joint. However, if the abutting jointis not abutted and securely bonded, a gap between the insulative sheathand the insulative layer permits shorting the flashover distance betweenthe energized contact extension and ground potential at an opening endof interface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an exemplary switchgear configuration;

FIG. 2 illustrates another side of the switchgear including a tap sidedoor that is positionable between an open position shown in FIG. 2 and aclosed position shown in FIG. 1 in an exemplary embodiment;

FIG. 3 is a perspective view of exemplary internal components of theswitchgear removed from the enclosure shown in FIG. 1 and without thesupporting frame, cables, or cable connectors for clarity;

FIG. 4 is a perspective view of another configuration of exemplaryinternal components of the switchgear illustrated removed from enclosureand without the supporting frame, cables, or cable connectors forclarity;

FIG. 5 is a perspective view of yet another configuration of exemplaryinternal components of the switchgear illustrated removed from enclosureand without the supporting frame, cables, or cable connectors forclarity;

FIG. 6 is a sectional view of bent bar zee connector that may be usedwith switchgear shown in FIGS. 3, 4, and 5;

FIG. 7 is a perspective view of an exemplary embodiment of a female-teethat may be used with switchgear shown in FIGS. 3, 4, and 5;

FIG. 8 is a perspective view of an exemplary embodiment of a male-teethat may be used with the switchgear shown in FIGS. 3, 4, and 5;

FIG. 9 is a perspective view of an exemplary embodiment of a “U”connector that may be used with the switchgear shown in FIGS. 3, 4, and5.

FIG. 10 is a longitudinal cross-sectional view of a conventional afemale connector, such as an elbow connector, electrically connected toa portion of a high-voltage circuit; and

FIG. 11 is a longitudinal cross-sectional view of a female connectorportion of a separable loadbreak connector system in accordance with anembodiment of the present invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following detailed description illustrates the invention by way ofexample and not by way of limitation. The description clearly enablesone skilled in the art to make and use the invention, describes severalembodiments, adaptations, variations, alternatives, and uses of theinvention, including what is presently believed to be the best mode ofcarrying out the invention.

High-voltage separable connectors interconnect sources of energy such astransformers to distribution networks or the like. Frequently, it isnecessary to connect and disconnect the electrical connectors. Theseconnectors typically feature an elbow component, which contains a maleconnector, and a bushing component, which contains a female connector.When the components are connected, elastomeric O-rings seal theconnection.

Disconnecting energized connectors is an operation known as a loadbreak.A problem known as “flashover” has been known to occur while switchingor separating loadbreak separable connectors. The male connector probeis typically maintained within the elbow, and the female connectorcontact is contained within the bushing. During a loadbreak operation,the elbow is pulled from the bushing using a hotstick to separate thecomponents. This, in effect, creates an open circuit. During separation,a phenomenon known as a flashover may occur where an arc from theenergized connector extends rapidly to a nearby ground. Existingconnector designs contain a number of arc extinguishing components sothat the devices can have loadbreak operations performed under energizedconditions with no flashover to ground occurring. The object of cautionis to control the arc and gases generated during loadmake and loadbreakoperations. Even with these precautions, however, flashovers haveoccurred on rare occasions. In a flashover, an arc extends from anenergized portion of one of the connectors and seeks a nearby ground.Flashovers commonly occur during the initial approximate one-inch ofseparation of the connectors from each other. The separation of theelbow from the bushing causes a partial vacuum to surround the energizedcomponents of the connector assembly. Because a partial vacuum presentsa lower dielectric strength than that of air at atmospheric pressure, aflashover is more likely to occur at the moment as the elastomeric sealbetween the components is broken and before atmospheric pressure isreestablished around the energized portions of the components. Also,after being connected over a long period of time, the elbow may adhereto the bushing interface so that the connectors cannot be easilydisengaged. This is known as a stuck condition, and greater force isrequired to separate the elbow resulting in a more rapid change inpressure and dielectric strength in the air surrounding the energizedcomponents.

During a flashover, an electrical arc between the energized componentsand ground may result which could cause damage to the equipment andpossibly create a power outage. The problem of flashovers involvesprincipally 25 KV and 35 KV loadbreak connectors but may also include 15KV connectors. In a solid dielectric insulated vacuum switch orinterrupter device, insulating layers keep internal conductive elementsof the device, which may be energized at either high voltage orelectrically grounded, electrically isolated from each other.Furthermore, an external ground shield is sometimes, but notnecessarily, provided to maintain outer surfaces of the device at groundpotential for safety reasons. This ground shield must also beelectrically isolated from the energized components. Electricalisolation between potentials is necessary to prevent faults in theelectrical system. In some cases, layers of electrical insulation mayseparate from each other due to manufacturing techniques that permitjoining the layers in a less robust way. Damage to the device itself orto surrounding equipment is also prevented, and people in the vicinityof the switchgear, including but not limited to maintenance workers andtechnicians, are protected from hazardous conditions. Providing suchinsulation in a cost effective manner so as to allow the device towithstand the applied voltage and to isolate the circuit when the switchcontacts are in the open position is a challenge.

Utility companies distribute power to customers using a network ofcables, switching stations and switchgear. Switchgear is high voltage(e.g. 5 kV-38 kV) equipment, typically subsurface, vault, or pad mountedand used to distribute and control power distribution in relativelysmall areas. Historically, switchgear is a box or container thatincludes bushings, insulation, a bus bar system and a collection ofactive switching elements. An active switching element is a device withan internal active component, such as a fuse, a switch, or aninterrupter, and external points of connection. In some active switchingelements, these external points of connection are bushings. Activeswitching elements are used to automatically, manually, or remotely openand/or close a circuit. It should be noted that active switchingelements that include switches or interrupters often include contacts ina vacuum, air, insulating oil, or dielectric gas. Distribution cablesare coupled to the bushings of the switchgear and have the capacity totransmit power at high voltages. The bushings in turn are coupled to, orform an integral part of, the active switching elements inside theswitchgear. The active switching elements are coupled by a bus barsystem to create the switchgear.

A mechanical connector connects two or more metallic elements by usingthreaded, crimp, or wedge connections. Typical mechanical busconnections consist of two or more conductors made from bars or braidswhich are secured together with a threaded bolt extending through holesin a flattened portion and secured by a bolt and a conductive memberwith internal threads. A typical mechanical connector to a flat busconductor surface is accomplished by threading a conductive member withinternal threads onto a threaded stud or a bolt. Push-on connectorsconsist of two or more metallic bus conductors that can be axiallyjoined. The components consist of a matching set of probes, rods, or‘male’ conductors that mate with finger-contacts, bores, or ‘female’conductors or contacts.

A conventional bus bar system generally includes electrically conductivemetal bars that are formed or bent around each other to maintainelectrical clearance with respect to each phase. The metal bars may beflexible or partially flexible to allow connection to two rigid members.The purpose of bus bar system is to conduct power from the source sideactive switching elements to the tap side active switching elements.Thus, if one of the active switching elements opens such that a sourceside or tap side cable is disconnected from the bus bar system, theremaining source and tap side cables remain connected and can transmitpower.

Insulation is provided between the bus bars and the active switchingelements to prevent electrical arcing. There are three common types ofinsulation typically used in conventional switchgear: oil, sulfurhexafluoride (SF₆) gas, and air. Each type of insulation insulates eachpart of the switchgear from the other parts of the switchgear (bus barand active switching elements), and from the outer surfaces of thecontainer of the switchgear.

It is desirable to provide a mounting structure and insulation forvacuum switch or interrupter devices and bus connecting systems thatimproves reliability of the switchgear as the contacts are opened andclosed, simplifies manufacture and assembly of the devices andassociated switchgear, and provides cost advantages in relation to knownswitch or interrupter devices and associated switchgear.

FIG. 1 illustrates an exemplary switchgear configuration 100. While oneexemplary switchgear 100 is described, it is understood that thebenefits of the invention accrue generally to switchgear of manyconfigurations, and that the switchgear 100 is but one potentialapplication of the switch or interrupter assemblies describedhereinbelow. Switchgear 100 is therefore illustrated and describedherein for illustrative purposes only, and the invention is not intendedto be limited to any particular type of switchgear configuration, suchas the switchgear 100.

As shown in FIG. 1, the switchgear 100 includes a protective enclosure102 having, for example, a source side door 104 positionable between anopen position (FIG. 1) and a closed position (FIG. 2). Latch elements106 and/or 108 may be used to lock source side door 104 in a closedposition. Inside the source side door 104 is a front plate 110 thatforms a portion of the enclosure 102. Cables 112 a-112 f may be coupledto a lower end of the enclosure 102 and are connected to activeswitching elements (described below) in the enclosure 102, and each ofthe cables 112 a-112 f typically carry power in three phases from twodifferent sources. For example, cables 112 a-112 c may carry,respectively, the A, B and C phases of power from source 1, and cables112 d-112 f may carry, respectively, the C, B and A phases of power fromsource 2.

Cables 112 a-112 f may be coupled to the front-plate 110 and switchgear100 through, for example, connector components 114 a-114 f that join thecables 112 a-112 f to respective switching elements (not shown inFIG. 1) in the enclosure 102. The switching elements may, in turn, becoupled to an internal bus bar system (not shown in FIG. 1) in theenclosure 102.

Handles or levers 116 a and 116 b are coupled to the enclosure 102 andmay operate active switchgear elements (described below) inside theswitchgear 100 to open or interrupt the flow of current through theswitchgear 100 via the cables 112 a-112 f and electrically isolate powersources 1 and 2 from load-side or power receiving devices. The cables112 a-112 c may be disconnected from the internal bus bar system bymanipulating the handle 116 a. Similarly, cables 112 d-112 f may bedisconnected from the internal bus bar system by manipulating the handle116 b. Handles 116 a and 116 b are mounted onto the front-plate 110 asshown in FIG. 1. In an exemplary embodiment, the active switch elementson the source side of the switchgear 100 are vacuum switch assemblies(described below), and the vacuum switch assemblies may be used incombination with other types of fault interrupters and fuses in variousembodiments of the invention.

One exemplary use of switchgear is to segregate a network of powerdistribution cables into sections such as, for example, by opening orclosing the switch elements. The switch elements may be opened orclosed, either locally or remotely, and the power supplied from onesource to the switchgear may be prevented from being conducted to theother side of the switchgear and/or to the bus. For example, by openingthe switch levers 116 a and 116 b, power from each of the sources 1 and2 on one side of the switchgear is prevented from being conducted to theother side of the switchgear and to the bus and the taps. In thismanner, a utility company is able to segregate a portion of the networkfor maintenance, either by choice, through the opening of switchgear, orautomatically for safety, through the use of a fuse or faultinterrupter, depending on the type of active switching elements includedin the switchgear.

FIG. 2 illustrates another side of the switchgear 100 including a tapside door 120 that is positionable between open (shown in FIG. 2) andclosed (FIG. 1) positions in an exemplary embodiment. Latch elements 122and/or 124 may be used to lock the tap side door 120 in the closedposition. Inside the tap door 120 is a front-plate 126 that defines aportion of the enclosure 102. Six cables 128 a-128 f may be connected toa lower side of the switchgear 100, and each of the respective cables128 a-128 f typically carries, for example, one phase of power away fromswitchgear 100. For example, cable 128 a may carry A phase power, cable128 b may carry B phase power and cable 128 c may carry C phase power.Similarly, cable 128 d may carry C phase power, cable 128 e may carry Bphase power and cable 128 f may carry A phase power. Connectors 130a-130 f connect cables 128 a-128 f to switchgear.

It should be noted that the exemplary switchgear 100 in FIGS. 1 and 2shows one only one exemplary type of phase configuration, namely an ABCCBA configuration from left to right in FIG. 2 so that the correspondingcables 128 a-128 c and 128 d-128 f carry the respective phases ABC andCBA in the respective tap 1 and tap 2. It is understood, however, thatother phase configurations may be provided in other embodiments,including but not limited AA BB CC so that cables 128 a and 128 b eachcarry A phases of current, cables 128 c and 128 d each carry B phases ofcurrent, and so that cables 128 e and 128 f each carry C phases ofcurrent. Still other configurations of switchgear may have one or moresources and taps on the same front-plate 110 (FIG. 1) or 126 (FIG. 2),or on the sides of the switchgear on one or more additional frontplates. It also contemplated that each phase may be designated by anumber, such as 1, 2 and 3, and that the switchgear may accommodate moreor less than three phases of power. Thus, a switchgear may have, forexample only, a configuration of 123456 654321 on the tap side of theswitchgear 100.

A frame may be positioned internal to the switchgear and provide supportfor the active switching elements as well as the bus bar system,described below. In other words, the frame holds the active switchingelements and bus bar system in place once they are coupled to the frame.The frame is oriented to allow portions of the active switchingelements, typically bushings, to protrude as a bushing plane so thatconnections to the various cables can be made.

In an exemplary embodiment, a lever or handle 132 a operates activeswitchgear elements, as described below, inside the switchgear 100 todisconnect cables 128 a, 128 b, 128 c from the internal bus bar system.Similarly, handles 132 b-132 d cause one of individual cables 128 d, 128e, 128 f to disconnect and connect, respectively, from the internal busbar system. In an exemplary embodiment, the active switchgear elementson the tap side of the switchgear 100 include vacuum interrupterassemblies (described below), and the vacuum interrupter assemblies maybe used in combination with fuses and various types of faultinterrupters in further and/or alternative embodiments of the invention.

FIG. 3 is a perspective view of exemplary internal components of theswitchgear 100 illustrated removed from enclosure 102 and without thesupporting frame, cables, or cable connectors for clarity. Switchelement assemblies 150 and fault interrupter assemblies 152 may bepositioned on opposites sides, for example, the source side and the tapside, respectively, of the switchgear assembly. Cable conduits 112 a-112f may contain respective cables to be connected to respective switchelement assemblies 150 a-150 c and 152 c-152 a, and cable conduits 128a-128 f (cable conduits 128 b-128 f not labeled in FIG. 3) may containrespective cables to be connected to the respective interrupter elementassemblies 154 a-154 c and 156 c-156 a.

A bus bar system 158 may be situated in between and may interconnect theswitch element or interrupter assemblies 150 a-c, 152 a-c, 154 a-c and156 a-c via various modular and interchangeable molded solid dielectricconnectors and bus components. The bus components include, but are notlimited to, a male-tee 160, a female-tee 162, a bent bar zee connector164, and a “U” connector 166. In different embodiments, the bus barsystem 158 includes solid dielectric coated metal bar members formed ina modular bus and connector system. The modular bus system may beassembled with mechanical and push-on connections into variousconfigurations, orientations of phase planes, and sizes of bus barsystems. In still another embodiment, molded solid dielectric bus barmembers may be provided in modular thini with push-on mechanicalconnectors to facilitate various configurations of bus bar systems witha reduced number of component parts.

In the exemplary embodiment, the switchgear is illustrated in a typicalsolid dielectric configuration, in that the bus work is compact withminimal clearance distances between different phase elements. Such closeclearances are possible because of the dielectric properties of themolded solid dielectric covering of the bus components. Phase “C” switchelement or interrupter assemblies 150 c, 152 c, 154 c, and 156 c arecoupled together using a male-tee 160 and a female-tee 162. Phase “B”switch element or interrupter assemblies 150 b, 152 b, 154 b, and 156 bare coupled together using two male-tees 160 and a “U” connector 166.Phase “A” switch element or interrupter assemblies 150 a, 152 a, 154 a,and 156 a are coupled together using two male-tees 160, two bent bar zeeconnectors 164 and a “U” connector 166. Utilizing bent bar zeeconnectors 164 permits moving bus components such as “U” connector 166from interfering with other bus components and maintaining apredetermined minimum clearance distance between the bus components,especially those having different voltages such as different phasecomponents. Without the unique dimensional features of bent bar zeeconnectors 164, additional bus components would be needed to accomplishcoupling of the incoming and outgoing cables. Such additional componentswould add to the complexity, cost, and maintenance of the installation.

FIG. 4 is a perspective view of another configuration of exemplaryinternal components of the switchgear 100 illustrated removed fromenclosure 102 and without the supporting frame, cables, or cableconnectors for clarity. Cable conduits 412 a-412 f may containrespective cables to be connected to respective switch elementassemblies 150 a-150 c and 152 c-152 a, and cable conduits 428 a-428 fmay contain respective cables to be connected to the respectiveinterrupter element assemblies 154 a-154 c and 156 c-156 a.

In the exemplary embodiment, the switchgear is illustrated in a firstretrofit configuration, in that the bus work being replaced may haverequired more clearance between bus components on the source side or thetap side. In such an instance, cable conduits 412 a-412 f may be spaceddifferently than cable conduits 428 a-428 f such that bus components arereconfigured to accommodate the different spacing. In known switchgearcomponents such accommodation in a retrofit application is accomplishedusing custom sized bus work coupled together using fasteners. In theexemplary embodiment, Phase “C” switch element or interrupter assemblies150 c, 152 c, 154 c, and 156 c are coupled together using a male-tee160, a female-tee 162, and two bushing extenders 430. Phase “B” switchelement or interrupter assemblies 150 b, 152 b, 154 b, and 156 b arecoupled together using two male-tees 160, two bent bar zee connectors164, and a “U” connector 166. Phase “A” switch element or interrupterassemblies 150 a, 152 a, 154 a, and 156 a are coupled together using twomale-tees 160, four bent bar zee connectors 164 and a “U” connector 166.Utilizing bent bar zee connectors 164 permits extending the buscomponents reach laterally to permit connection of switch element orinterrupter assemblies 156 a to 152 a, 156 b to 152 a, 154 b to 150 b,and 154 a to 150 a. Without using bent bar zee connectors 164, the buscomponents would require ninety degree components and various lengths ofshort jumpers to permit maintaining a clearance distance betweendifferent adjacent phases.

FIG. 5 is a perspective view of yet another configuration of exemplaryinternal components of the switchgear 100 illustrated removed fromenclosure 102 and without the supporting frame, cables, or cableconnectors for clarity. Cable conduits 512 a-512 f may containrespective cables to be connected to respective switch elementassemblies 150 a-150 c and 152 c-152 a, and cable conduits 528 a-528 f(cable conduits 528 a and 528 b not labeled in FIG. 5) may containrespective cables to be connected to the respective interrupter elementassemblies 154 a-154 c and 156 c-156 a.

In the exemplary embodiment, the switchgear is illustrated in a secondretrofit configuration, in that the bus work being replaced may haverequired more clearance on both the source side or the tap side than ispossible with a solid dielectric bus system. In such an instance, cableconduits 412 a-412 f may be spaced differently than cable conduits 428a-428 f such that bus components are reconfigured to accommodate thedifferent spacing. In known switchgear components such accommodation ina retrofit application is accomplished using custom sized bus workcoupled together using fasteners. However, using the modular moldedsolid dielectric bus components of various embodiments of the presentinvention, interchangeable bus components can be used to accommodate aplurality of different cable conduit configurations. In the exemplaryembodiment, Phase “C” switch element or interrupter assemblies 150 c,152 c, 154 c, and 156 c are coupled together using a male-tee 160, afemale-tee 162, and two bent bar zee connectors 164. Phase “B” switchelement or interrupter assemblies 150 b, 152 b, 154 b, and 156 b arecoupled together using two male-tees 160, two bushing extenders 430, twobent bar zee connectors 164, and a “U” connector 166. Phase “A” switchelement or interrupter assemblies 150 a, 152 a, 154 a, and 156 a arecoupled together using two male-tees 160, two bent bar zee connectors164 and two “U” connectors 166 and a short-U connector 530. Bent bar zeeconnectors 164 permits maintaining a clearance distance betweendifferent adjacent phases without requiring ninety degree components andvarious lengths of short jumpers to permit while coupling bus componentswith different lateral spacing requirements.

FIG. 6 is a sectional view of bent bar zee connector 164 that may beused with switchgear 100 (shown in FIGS. 3, 4, and 5). In the exemplaryembodiment, bent bar zee connector 164 is formed of an insulatedconnector housing 602. A bent bus bar 604 interconnects a contact probe606 in a female housing end 608 and a contact assembly 610 in a malehousing end 612. Bent bus bar 604 comprises a contact probe portion 614and a contact assembly portion 616 offset with respect to each other insubstantially parallel alignment by a bus bar 618 extending therebetweenand forming an oblique angle with contact probe portion 614 and contactassembly portion 616. Contact probe 606 and contact assembly 610 extendaway from contact probe portion 614 and a contact assembly portion 616,respectively in opposite directions. Contact probe 606 and contactassembly 610 are spaced apart a distance 620. Contact probe 606 andcontact assembly 610 are formed as complementary electrical connectingcontacts that are configured to mate to bus components having similarlymatching mating components. Accordingly, contact probe 606 is configuredto mate to a contact assembly 610 of another bus component and contactassembly 610 is configured to mate to a contact probe 606 of another buscomponent. As such various configurations of bus components may beassembled into systems capable of joining a plurality of configurationsof preexisting switchgear cable connectors.

EPDM rubber insulation, for example, may surround bent bus bar 604,contact probe 606, and contact assembly 610, and may define theinterfaces 622 between female housing end 608 and male housing end 612.

While assembly 164 is formed into a Z-shaped configuration havingsubstantially equal legs in the exemplary embodiment, it is appreciatedthat connector assembly 164 may be alternatively shaped in otherconfigurations while still providing the modular interconnectingfunctionality of embodiments of the present invention. For example,female housing end 608 and male housing end 612 may be unequal in size,shape and dimension such as length, and female housing end 608 and malehousing end 612 need not extend from contact probe portion 614 andcontact assembly portion 616 at right angles in other embodiments.

Notably, and unlike known connectors, connector assembly 164 includes abent bus bar that permits interconnection of other bus components invarious configurations for connecting cable connectors that are fixed ina plurality of different configurations by existing conduit orencasement in concrete or the ground.

In the exemplary embodiment connector assembly 164 is used with a 600 A,21.1 kV class loadbreak connector for use with medium voltage switchgearor other electrical apparatus in a power distribution network of above600V. It is appreciated, however, that the connector concepts describedherein could be used in other types of connectors and in other types ofdistribution systems, such as high voltage systems, as desired.

FIG. 7 is a perspective view of an exemplary embodiment of a female-tee162 that may be used with switchgear 100 (shown in FIGS. 3, 4, and 5).In the exemplary embodiment, female-tee 162 includes a female housingend 608 and a male housing end 612 extending away from each other atsubstantially right angles. Female housing end 608 and male housing end612 are complementary to similar female housing ends 608 and malehousing ends 612 of other switchgear 100 bus components.

FIG. 8 is a perspective view of an exemplary embodiment of a male-tee160 that may be used with switchgear 100 (shown in FIGS. 3, 4, and 5).In the exemplary embodiment, male-tee 160 includes three male housingends 612 extending away from each other at substantially right angles.Male housing ends 612 are complementary to female housing ends 608 ofother switchgear 100 bus components.

FIG. 9 is a perspective view of an exemplary embodiment of a “U”connector 166 that may be used with switchgear 100 (shown in FIGS. 3, 4,and 5). In the exemplary embodiment, “U” connector 166 includes two malehousing ends 612 and a bus bar 902 extending between a coupling end 904of each male housing end 612. Typically, male housing ends 612 extendaway from bus bar 902 in substantially the same direction, however malehousing ends 612 may extend in other directions and at different anglesin other embodiments of the present invention. Male housing ends 612 arespaced a distance 906 apart from a centerline 908 to a centerline 910.Distance 906 is selected based on standard spacing considerations fornew installations and retrofit applications. In the exemplaryembodiment, distance 906 is approximately twenty-four inches. Malehousing ends 612 are complementary to female housing ends of otherswitchgear bus components.

FIG. 10 is a longitudinal cross-sectional view of a conventional afemale connector 1020, such as an elbow connector, electricallyconnected to a portion of a high-voltage circuit (not shown). Femaleconnector 1020 may form a portion of a separable loadbreak connectorsystem (male portion not shown) that may be utilized to connect anddisconnect cables to switchgear 100 under energized circuit conditionsat rated voltage and under electrical load current conditions. As shown,female contact connector 1020 is in the form of a cable terminationdevice, such as an elbow. Male and female contact connectors arereversibly connectable and respectively interfit to achieve electricalconnection. In the preferred embodiment described herein, the connectorassembly is a 200 A, 250 KV class connector assembly.

Female connector 1020 includes an elastomeric and electrically-resistivehousing 1022 of a material such as EPDM(ethylene-propylene-dienemonomer) rubber which is provided on its outersurface with a semiconductive shield layer 1024 that may be grounded bymeans of a perforated grounding tab (not shown). Female connector 1020is generally elbow-shaped, being formed of an upper horizontal portion1028 and a lower vertical portion (not shown) connected at a centralportion 1032. A pulling eye 1034 extends horizontally from the centralportion 1032. Horizontally-oriented and generally conical bore 1038 isdisposed within the housing 1022. A semiconductive insert 1040 such as afaraday cage is contained within the housing 1022. Semiconductive insert1040 is configured to maintain an electric potential substantially equalto the electric potential of contact probe 1054. Faraday cage 1040facilitates reducing corona discharges within an interface 1041 whenconnector 1020 is mated, for example, to the male mating connector. Ahorizontally-disposed portion 1044 of the insert 1040 extends into theupper portion 1028 of the connector 1020 and presents an inner radialsurface 1046 which defines a conically-shaped recess 1048. Insert 1040also presents an annular locking ring 1050 which is inwardly directedwithin the recess 1048 from the inner radial surface 1046 of the insert1040. The locking ring 1050 divides the inner radial surface 1046 into arecessed area 1047 and an extended area 1049.

An insulative layer 1052 of electrically-resistive material is disposedwithin the recess 1048 of the insert 1040. The insulative layer 1052 ispreferably also made of EPDM and may be unitarily molded with portionsof the housing 1022 during manufacture. The insulative layer 1052preferably extends from the inner surface of the bore 1038 along theinner surface 1046 of the insert 1040 to at least the locking ring 1050so that the extended area 1049 of the inner surface 1046 is insulated.Additionally, the recessed area 1047 of the insert 1040 may beinsulated.

A probe assembly 1054 is largely contained within housing 1022 andaligned down the axis 1055 of the conical bore 1038 of insert 40. Theprobe assembly 1054 threadably engages a conductor contact 1056. Theprobe assembly 1054 includes a contact element or probe 1058 that isformed of a material such as copper and extends horizontally from theconductor contact 1056 into the bore 1038 of the upper portion 1028 andthe recess 1048 of the insert 1040. At a distal end 1057 of the probe1058 extends an arc follower 1060 of ablative material. A preferredablative material for the arc follower 1060 is acetal co-polymer resinloaded with finely divided melamine. The ablative material is typicallyinjection molded onto a reinforcing pin.

An insulative sheath 1066 is disposed about the portions of the exteriorof the probe 1058. The sheath 1066 does not cover the entire length ofthe probe 1058 as at least the distal end 1057 of the probe 1058proximate to the arc follower 1060 will need to be remain unsheathed sothat an electrical connection may be made. It is preferred, however,that the sheath 1066 should at least extend to and abut the recessedarea 1047 of the inner radial surface 1046 of insert 1040. Insulativesheath 1066 and insulative layer 1052 facilitate providing greaterdistance from the energized arc follower 1060 to ground potential at anopening end of interface 1041 when connector 1020 is being removed fromthe male mating connector. Insulative layer 1052 is formed to an innersurface of insert 1040. During the process of assembling connector 1020,insulative sheath 1066 and insulative layer 1052 are formed separatelyand insulative layer 1052 is expected to bond securely to insulativesheath 1066 at an abutting joint 1070. However, if joint 1070 is notabutted and securely bonded, a gap between insulative sheath 1066 andinsulative layer 1052 permits shorting the flashover distance betweenthe energized contact extension 1060 and ground potential at an openingend of interface 1041.

Female connector 1020 may be configured as an elbow connector thatengages the male mating connector via interface 1041 on one end, andengages, for example, a fuse element module on another end (not shown inFIG. 10. Alternatively, connector 1020 may be configured into anothertype of connector having any shape or configuration desired. Connector1020 may also be configured as a protective cap for use with the malemating connector that is energized at rated voltage as described above.

FIG. 11 is a longitudinal cross-sectional view of a female connector1100 portion of a separable loadbreak connector system (male portion notshown) in accordance with an embodiment of the present invention. Femaleconnector 1120 includes an elastomeric and electrically-resistivehousing 1122 of a material such as EPDM(ethylene-propylene-dienemonomer) rubber which is provided on its outersurface with a semiconductive shield layer 1124 that may be grounded bymeans of a perforated grounding tab (not shown). Female connector 1120is generally elbow-shaped, being formed of an upper horizontal portion1128 and a lower vertical portion (not shown) connected at a centralportion 1132. A pulling eye 1134 extends horizontally from the centralportion 1132. Horizontally-oriented and generally conical bore 1138 isdisposed within the housing 1122. A semiconductive insert 1140 such as afaraday cage is contained within the housing 1122. Semiconductive insert1140 is configured to maintain an electric potential substantially equalto the electric potential of contact probe 1154. Faraday cage 1140facilitates reducing corona discharges within an interface 1141 whenconnector 1120 is mated, for example, to the male mating connector. Ahorizontally-disposed portion 1144 of the insert 1140 extends into theupper portion 1128 of the connector 1120 and presents an inner radialsurface 1146 which defines a conically-shaped recess 1148. Insert 1140also presents an annular locking ring 1150 which is inwardly directedwithin the recess 1148 from the inner radial surface 1146 of the insert1140. The locking ring 1150 divides the inner radial surface 1146 into arecessed area 1147 and an extended area 1149.

An insulative layer 1152 of electrically-resistive material is disposedwithin the recess 1148 of the insert 1140. The insulative layer 1152 ispreferably also made of EPDM and may be unitarily molded with portionsof the housing 1122 during manufacture. The insulative layer 1152preferably extends from the inner surface of the bore 1138 along theinner surface 1146 of the insert 1140 to at least the locking ring 1150so that the extended area 1149 of the inner surface 1146 is insulated.Additionally, the recessed area 1147 of the insert 1140 may beinsulated.

A probe assembly 1154 is largely contained within housing 1122 andaligned down the axis 1155 of the conical bore 1138 of insert 40. Theprobe assembly 1154 threadably engages a conductor contact 1156. Theprobe assembly 1154 includes a contact element or probe 1158 that isformed of a material such as copper and extends horizontally from theconductor contact 1156 into the bore 1138 of the upper portion 1128 andthe recess 1148 of the insert 1140. At a distal end 1157 of the probe1158 extends an arc follower 1160 of ablative material. A preferredablative material for the arc follower 1160 is acetal co-polymer resinloaded with finely divided melamine. The ablative material is typicallyinjection molded onto a reinforcing pin.

An insulative sheath 1166 is disposed about the portions of the exteriorof the probe 1158. The sheath 1166 does not cover the entire length ofthe probe 1158 as at least the distal end 1157 of the probe 1158proximate to the arc follower 1160 will need to be remain unsheathed sothat an electrical connection may be made. It is preferred, however,that the sheath 1166 should at least extend to the recessed area 1147 ofthe inner radial surface 1146 of insert 1140. Insulative sheath 1166 andinsulative layer 1152 facilitate providing greater distance from theenergized arc follower 1160 to ground potential at an opening end ofinterface 1141 when connector 1120 is being removed from the male matingconnector. Insulative layer 1152 is formed to an inner surface of insert1140. During the process of assembling connector 1120, insulative sheath1166 and insulative layer 1152 are formed separately and insulativelayer 1152 is expected to bond securely to insulative sheath 1166 at anoverlapping joint 1170. In the exemplary embodiment, insulative sheath1166 extends along probe 1158 into recessed area 1147 and forms aradially outwardly extending annular flange 1172 at the base of probe1158. Flange 1172 extends towards an inner surface of insert 1140 and ina preferred embodiment extends into contact with horizontally-disposedportion 1144 of the insert 1140. Insulative layer 1152 extends axiallyalong horizontally-disposed portion 1144 of the insert 1140 and forms aradially inwardly extending flange 1174 that overrides radiallyoutwardly extending annular flange 1172 of sheath 1166. In the presentconfiguration sheath 1166 and insulative layer 1152 do not meet at anabutting joint but rather are bonded together at an overlapping joint1170. In the exemplary embodiment, overlapping joint is configured toprovide additional bonding surface between radially outwardly extendingannular flange 1172 and radially inwardly extending flange 1174 thanwould be afforded by an abutting joint between flange 1172 and flange1174.

Female connector 1120 may be configured to perform the functionsdescribed above with the connecting pieces described above with respectto the various figures illustrated the various embodiments of thepresent invention.

In first exemplary embodiment a bus connector includes a solid bus barincluding at least one oblique bend, a first electrical connectorcoupled to a first end of the bus bar, and a second electrical connectorcoupled to a second end of the bus bar. Optionally, the first electricalconnector and/or the second electrical connector extend perpendicularlyaway from the bus bar. The bus connector may further include a layer ofsolid insulation of rubber and/or plastic at least partially surroundingthe bus bar and the first and/or second connectors. The bus connectormay further include a semiconductive shield layer covering at least aportion of the insulation layer.

An insulation layer may surround the bus bar and the first and secondconnectors wherein the connector further includes a semiconductiveshield layer covering at least a portion of the insulation layer.Optionally, the first electrical connector or the second electricalconnector includes a contact probe and the other of the first electricalconnector or the second electrical connector includes a plurality ofcontact fingers configured to receive a contact probe from a matingconnector. Optionally, the bus bar includes a first oblique bendproximate the first end of the bus bar and a second oblique bend formedproximate to the second end of the bus bar. The first oblique bend andthe second oblique bend may be formed in opposite directions andsubstantially equal magnitudes such that the first end and the secondend are substantially parallel proximate to the second end of the busbar. In another optional embodiment, the first and second connectorsextend from a respective end of the bus bar in opposite directions suchthat a longitudinal axis of each of the first and second connectors aresubstantially parallel with respect to each other. Also optionally, atleast one of the first electrical connector and the second electricalconnector may extend perpendicularly away from the bus bar.

In a further optional embodiment, the bus connector may include a firstconnector member that includes an electrically-resistive housing havinga generally conically-shaped interior bore, a semiconductive insertdisposed within a portion of the bore, the insert presenting an innerradial surface which defines a generally conically-shaped recess, anelongated probe disposed within the housing, the probe assembly having asheath of insulative material over at least a portion of its length andextending in a radially outward direction from a base of the probe, andan electrically-resistive insulative layer disposed extending from theconically-shaped interior bore along portions of the inner radialsurface of the semiconductive insert and extending radially inwardly inoverlapping engagement with a portion of the sheath.

In another embodiment, an electrical connector includes a firstconnector member that includes an electrically-resistive housing havinga generally conically-shaped interior bore and a semiconductive insertdisposed within a portion of the bore wherein the insert presents aninner radial surface which defines a generally conically-shaped recess.The electrical connector also includes an elongated probe assemblydisposed within the housing having a sheath of insulative material overat least a portion of its length and extending in a radially outwarddirection from a base of the probe assembly. The electrical connectoralso includes an electrically-resistive insulative layer disposedextending from the conically-shaped interior bore along portions of theinner radial surface of the semiconductive insert and extending radiallyinwardly in overlapping engagement with the radially outwardly extendingportion of the sheath.

Optionally, the connector includes a solid bus bar including at leastone oblique bend wherein the bus bar is electrically coupled to thefirst connector member such that the first connector member extends fromthe bus bar substantially perpendicularly and the second connectormember is electrically coupled to an opposite end of the bus bar. Thebus bar may be electrically coupled to the second connector member suchthat the second connector member extends from the bus bar substantiallyperpendicularly.

In another embodiment, a bus bar connector kit includes a plurality ofinterchangeable connector assemblies wherein each connector assemblyincludes a solid bar substantially covered by a solid substantiallyhomogenous insulation material. The insulation material is at leastpartially surrounded by a substantially homogeneous semiconductivematerial and each of the plurality of interchangeable connectorassemblies includes at least one first connector member configured tomate with a complementary second connector member of another of theplurality of interchangeable connector assemblies.

Optionally, the bus bar connector kit includes an electrically-resistivehousing having a generally conically-shaped interior bore and asemiconductive insert disposed within a portion of the bore, the insertpresenting an inner radial surface which defines a generallyconically-shaped recess. The housing also optionally includes anelongated probe disposed within the housing that has a sheath ofinsulative material over at least a portion of its length and extendingin a radially outward direction from a base of the probe. The housingalso optionally includes an electrically-resistive insulative layerdisposed extending from the conically-shaped interior bore alongportions of the inner radial surface of the semiconductive insert andextending radially inwardly in overlapping engagement with a portion ofthe sheath.

Optionally, the bus bar connector kit includes a Z-shaped connectorassembly including a solid bus bar having at least one oblique bend, afirst electrical connector coupled to a first end of the bus bar, and asecond electrical connector coupled to a second end of the bus bar. Thebus bar connector kit may also include a U-shaped connector assemblyincluding a solid straight bus bar, a first electrical connector coupledto a first end of the bus bar, and a second electrical connector coupledto a second end of the bus bar wherein the first connector extends fromthe bus bar in a substantially perpendicular direction and the secondconnector extends from the bus bar in the substantially perpendiculardirection.

The bus bar connector kit may also include a T-shaped connector assemblyincluding at least one first connector member and at least one secondconnector member wherein like connector members are oriented in oppositedirections and the other connector member is oriented approximately 90degrees with respect to the like connector members. A The bus barconnector kit may also include a T-shaped connector assembly includingthree of at least one of a first connector member and a second connectormember wherein two connector members are oriented in opposite directionsand the third connector member is oriented approximately 90 degrees withrespect to the like connector members.

In another embodiment a method for reducing the risk of flashoverbetween electrical connectors during disconnection of a first and asecond connectors includes insulating a conductive portion of the firstconnector using an insulating sheath, insulating a semiconductiveportion of the first connector using an insulative layer, and joiningthe insulating sheath and the insulative layer in an overlapping bondedconnection. Optionally, the first connector includes a connecting probeand the step of insulating the conductive portion includes insulatingthe connecting probe using an insulating sheath. The first connector mayinclude a semiconductive insert and insulating a semiconductive portionof the first connector may include insulating the semiconductive insertusing an insulative layer. The first connector may also include aconnecting probe and joining the insulating sheath and the insulativelayer includes joining the insulating sheath and the insulative layer atoverlapping ends of the insulating sheath and the insulative layerproximate a base of the connecting probe.

While the invention has been described in terms of various specificembodiments, those skilled in the art will recognize that the inventioncan be practiced with modification within the spirit and scope of theclaims.

1. A bus bar connector kit, comprising: a plurality of interchangeableconnector assemblies each comprising a solid bus bar substantiallycovered by a solid substantially homogenous insulation material, theinsulation material at least partially surrounded by a substantiallyhomogeneous semiconductive material, each of the plurality ofinterchangeable connector assemblies comprising at least one electricalconnector configured to mate with a complementary electrical connectorof another of the plurality of interchangeable connector assemblies,wherein at least one of the electrical connectors of at least one of theplurality of interchangeable connector assemblies comprises anelectrically-resistive housing having a generally conically-shapedinterior bore, a semiconductive insert disposed within a portion of theinterior bore, the semiconductive insert comprising an inner radialsurface that defines a generally conically-shaped recess, an elongatedprobe assembly disposed within the housing, the probe assemblycomprising a probe, and a sheath of insulative material disposed over atleast a portion of a length of the probe, a portion of the sheathextending in a radially outward direction from a base of the probe, andan electrically-resistive insulative layer extending from theconically-shaped interior bore along at least a portion of the innerradial surface of the semiconductive insert and extending radiallyinwardly in overlapping engagement with a portion of the sheath.
 2. Theconnector of claim 1, wherein the insulative layer extends radiallyinwardly in overlapping engagement with the radially outwardly extendingportion of the sheath.
 3. The connector of claim 1, wherein the at leastone of the interchangeable connector assemblies comprises a U-shapedconnector assembly comprising: a solid straight bus bar; a firstelectrical connector coupled to a first end of the bus bar, the firstelectrical connector extending from the bus bar in a substantiallyperpendicular direction; and a second electrical connector coupled to asecond end of the bus bar, the second electrical connector extendingfrom the bus bar in the substantially perpendicular direction.
 4. Theconnector of claim 1, wherein the at least one of the interchangeableconnector assemblies comprises a T-shaped connector assembly comprisingfirst, second, and third electrical connectors, wherein the first andsecond electrical connectors are oriented in opposite directions withrespect to one another, and the third electrical connector is orientedapproximately 90 degrees with respect to the first and second electricalconnectors.
 5. A bus bar connector kit, comprising: a plurality ofinterchangeable connector assemblies each comprising a solid bus barsubstantially covered by a solid substantially homogenous insulationmaterial, the insulation material at least partially surrounded by asubstantially homogeneous semiconductive material, each of the pluralityof interchangeable connector assemblies comprising at least oneelectrical connector configured to mate with a complementary electricalconnector of another of the plurality of interchangeable connectorassemblies, wherein at least one of the electrical connectors of atleast one of the plurality of interchangeable connector assembliescomprises a first connector member comprising an electrically-resistivehousing having a generally conically-shaped interior bore, asemiconductive insert disposed within a portion of the interior bore,the semiconductive insert comprising an inner radial surface thatdefines a generally conically-shaped recess, an elongated probe assemblydisposed within the housing, the probe assembly comprising a probe, anda sheath of insulative material disposed over at least a portion of alength of the probe, a portion of the sheath extending in a radiallyoutward direction from a base of the probe, and anelectrically-resistive insulative layer extending from theconically-shaped interior bore along at least a portion of the innerradial surface of the semiconductive insert and extending radiallyinwardly in overlapping engagement with a portion of the sheath; the busbar comprising at least one oblique bend, the first connector memberbeing electrically coupled to a first end of the bus bar such that thefirst connector member extends from the bus bar substantiallyperpendicularly; and a second connector member electrically coupled to asecond end of the bus bar, the second end being disposed opposite thefirst end.
 6. The connector of claim 5, wherein the insulative layerextends radially inwardly in overlapping engagement with the radiallyoutwardly extending portion of the sheath.
 7. The connector of claim 5,wherein the bus bar is electrically coupled to the second connectormember such that the second connector member extends from the bus barsubstantially perpendicularly.